High-tech system will track sturgeon
Last week the Milwaukee River received Wisconsin's first installation of a permanent, cross-stream sensor system to monitor fish implanted with passive integrated transponders, or PIT tags.
To borrow from astronaut Neal Armstrong, it was one mid-level electronic feat but one huge leap for lake sturgeon management.
"It's basically light-years worth of an advancement in our capabilities," said Brad Eggold, Department of Natural Resources fisheries manager.
The high-tech equipment is designed primarily to detect and record migrations of sturgeon as part of the native species' restoration in the river. But it will work on any PIT-tagged fish.
Since 2006 young sturgeon, most reared and tagged at Riveredge Nature Center in Saukville, have been released in the Milwaukee River or harbor.
It's hoped the fish will survive, grow and return at maturity to spawn and reestablish a naturally-reproducing population of sturgeon.
No spawning activity has been detected yet. Sturgeon take 15 to 20 years to mature.
But some large sturgeon have been captured in the Milwaukee, including one PIT-tagged fish last April.
However it's not feasible nor desirable to try to net every migrating sturgeon.
That's where the new technology comes in. It will allow 24/7/365 monitoring of sturgeon movements in the river, Eggold said, without disturbing a single fish.
The system, called a PIT tag array, includes two antennas placed across the river about 125 feet apart.
The PIT tags are about the size of a grain of rice and have become a standard tool for scientists to study fish movements. They are implanted via a syringe.
The technology is virtually identical to that used to "chip" dogs and cats and allows individual fish to be identified.
The array's sensors are housed in synthetic pipe sections anchored to the river bottom.
If a fish with a PIT tag swims over the device, a signal is sent through cables to a master controller and transmitted electronically to the DNR. The "hit" report includes the unique 15-digit tag number of the fish, allowing biologists to know the fish's species, age and origin.
The system was put in place last week by the DNR, including fisheries biologist Aaron Schiller, and a crew from the manufacturer, Biomark, Inc. of Boise, Idaho.
Partners in the project include the DNR, the Urban Ecology Center and the Milwaukee County Parks System.
The equipment cost about $80,000 and installation was about $20,000, Eggold said.
The project is being funded with grants from the Fund for Lake Michigan and the Great Lakes Fisheries Trust.
The Milwaukee River installation is the first such permanent, cross-river array in the state, but it won't be for long.
Another is planned to be placed on the Peshtigo River, perhaps later this year.
And regionally, the Wisconsin work is part of a larger collaborative project with the Michigan DNR, Little River Band of Ottawa Indians and U.S. Fish and Wildlife Service.
At least two rivers in Michigan will also feature the technology.
By having multiple arrays spread out in Lake Michigan tributaries, scientists hope to start to get a handle on the straying rates of sturgeon and the success of the streamside rearing facilities as aides to sturgeon restoration compared to traditional hatcheries.
The Little River Band of Ottawa operate the original "sturgeon wagon" on the Manistee River in Michigan. The Riveredge facility was modeled after the Manistee design, Eggold said.
Over the last 15 years, 17,886 young sturgeon have been produced at Riveredge and released into the Milwaukee River or harbor, said Mary Holleback, Riveredge senior naturalist who runs the sturgeon project.
The Riveredge hatchery was shuttered in 2020 due to the coronavirus pandemic.
But this year it's up and running and holding about 2,000 young sturgeon as of this week.
The PIT tag array took about three days to install and get running, Schiller said. The lack of rain provided low water and optimal conditions in the Milwaukee.
The location is about 4 miles upstream from the river's mouth.
It didn't take long for the system to detect a tagged animal. The first report came in at 3:41 a.m. July 28, hours after the system went live, Schiller said.
What was it? The DNR is tracking the number but hadn't determined the species as of Wednesday.
The tags are also used in turtles and other animals.
It's hoped next late winter and early spring the system will report a lot of sturgeon migrating upriver.
"The treasure trove of data we're going to get off this we expect to be nothing short of phenomenal," Eggold said.
Will the system detect the first eggbearing female sturgeon in the Milwaukee in more than 100 years?
I know I'm part of a legion who hopes the answer is yes.